The present invention relates to liquid thickened detergent compositions containing low molecular weight organic diamines. More particularly, the invention is directed to liquid thickened detergent compositions for hand dishwashing which have improved grease removal performance and benefits in sudsing. The detergents of this invention also have improved low temperature stability properties and superior dissolution, as well as improved tough food stain removal, and antibacterial properties.
When formulated into hand dishwashing detergents at a pH of above about 8.0, the diamines are more effective as replacements for the low-level use of Ca/Mg ions as surfactancy boosters long known in the dishwashing art. The diamines provide simultaneous benefits in grease cleaning, sudsing, dissolution and low temperature stability, without the shortcomings associated with Ca/Mg.
Typical commercial hand dishwashing compositions incorporate divalent ions (Mg, Ca) to ensure adequate grease performance in soft water. However, the presence of divalent ions in formulas containing anionic, nonionic, or additional surfactants (e.g., alkyl dimethyl amine oxide, alkyl ethoxylate, alkanoyl glucose amide, alkyl betaines) leads to slower rates of product mixing with water (and hence poor flash foam), poor rinsing, and poor low temperature stability properties. Moreover, preparation of stable dishwashing detergents containing Ca/Mg is very difficult due to the precipitation issues associated with Ca and Mg as pH increases.
It is also desirable that liquid dishwashing compositions be formulated as thick liquids, mainly for ease of dosing and control of spreading when applied directly onto dishes. Thick compositions are also desirable when the composition is to be applied directly on an implement. Finally, consumers tend to equate product thickness with richness and quality of the product. However, it is essential that such a thick product should retain an acceptable dissolution profile. The dissolution problem is made even greater when such a thickened product contains divalent ions such as Ca and Mg.
Consequently, there remains the need for a thick detergent composition suitable for hand dishwashing, which is stable at low temperatures, and additionally can provide grease removal improved cleaning of tough food stains, superior dissolution and removal of grease/oil when compared to the use of Mg or Ca ions in conventional detergent compositions.
U.S. Pat. No. 4,556,509 and JP 63131124-A 88/06/03.
It has now been determined that the use of certain organic diamines, as outlined in detail below, with surfactants in dishcare compositions with pH""sxcx9c8.0-12 (measured at 10% solution) leads to improved cleaning of tough food stains, superior dissolution and removal of grease/oil when compared to the use of Mg or Ca ions in conventional detergent compositions. Unexpectedly, these organic diamines also improve suds stability in the presence of soils, esp. soils containing fatty acids and proteins.
Further, the strong grease removal performance of the diamines discussed herein allows elimination of Mg/Ca ions from the formulation while maintaining benefits in grease performance. The removal of Mg/Ca additionally leads to improved benefits in dissolution, rinsing and low temperature product stability.
The diamines of this invention in combination with surfactants also provides sensory benefits. It has been found that the presence of this composition produces a xe2x80x9csilkyxe2x80x9d feel to wash liquor and a feeling of xe2x80x9cmildnessxe2x80x9d to the skin. The diamines are also found to produce antibacterial benefits to the wash liquor. However, the specific compositions presented herein are especially designed for dishwashing having relatively high pH""s, detersive surfactants, and optional enzymes, all of which would be undesirable in contact lens cleaners.
The present invention encompasses a thick hand dishwashing, comprising:
a) a low molecular weight organic diamine having a pK1 and a pK2, wherein the pK1 and the pK2 of said diamine are both in the range of from about 8.0 to about 11.5; and
b) an anionic surfactant;
c) a co-surfactant selected from the group consisting of amine oxides, polyhydroxy fatty acid amides, betaines, nonionic surfactants and alkyl-polyglycosides, or mixtures thereof;
said composition being substantially free of magnesium and calcium salts and water miscible solvents;
wherein the pH of said composition (as measured as 10% aqueous solution) is from about 8.0 to about 12. The compositions herein are generally clear products.
In a further aspect the present invention also encompasses a method for improving the dissolution of a thick dishwashing composition; the method comprising the step of incorporating into the composition a dissolution improving amount of a low molecular weight organic diamine having a pK1 and a pK2, wherein the pK1 and the pK2 of the diamine are both in the range of from about 8.0 to about 11.5; wherein the composition being substantially free of magnesium and calcium salts and water-miscible solvents. All parts, percentages and ratios used herein are expressed as percent weight unless otherwise specified. All documents cited are, in relevant part, incorporated herein by reference.